Those are actually two different services. TechTracker scans your computer for installed software and available updates while the Watch List lists software you've downloaded from CNET and/or added to the list, resulting in an email sent to you whenever a new version comes out.

If you're using the Watch List, you can check the box to the left of the listing and click the Delete button. On the other hand, if you're using TechTracker, you can either a.) uninstall the software from your computer and remove any remaining remnants that TechTracker may be detecting or b.) click Info & Settings and choose to hide the application from the list. Note that you must have Javascript enabled in your browser to perform those actions.

Hope this helps,
John